Human nutrition

Question 1

Types of digestion:

Answer 1

mechanical, chemical and physical

Question 2

Molecular formation of carbohydrates:

Answer 2

• made up of carbon, hydrogen and oxygen
• complex carbohydrates: starch and glycogen (made up of maltose and glucose)

e.g maltose -> starch

Question 3

Molecular formula of lipids (oils and fats):

Answer 3

• built from fatty acids and glycerol
• molecules contain carbon, hydrogen and oxygen

glycerol + fatty acids -> lipids

Question 4

Molecular formula of proteins:

Answer 4

• long chains of amino acids
• contain carbon, nitrogen, hydrogen and oxygen

Question 5

Carbohydrates in a balanced diet:

Answer 5

• found in pasta, rice and sugar
• provides energy

Question 6

Lipids in a balanced diet:

Answer 6

• oily fish, butter
• provides energy, acts as an energy store, insulation

Question 7

Proteins in a balanced diet:

Answer 7

• meat and fish
• needed for growth and repair of tissues, provide energy for emergencies

Question 8

Vitamins in a balanced diet:

Answer 8

Vitamin A: liver, helps improve vision and keeps skin and hair healthy

Vitamin C: fruit e.g citrus, prevent scurvy

Vitamin D: Eggs, needed for calcium absorption

Question 9

Mineral ions in a balanced diet:

Answer 9

Calcium: milk and cheese, needed to make bones and teeth

Iron: red meat, needed to make haemoglobin for healthy blood

Question 10

Water in a balanced diet:

Answer 10

• every bodily function relies on water, we need a constant supply of water since we lose a-lot of it due to urination, breathing and sweating

Question 11

Dietary fibre in a balanced diet:

Answer 11

• wholemeal bread and fruit
• aids the movement of foods through the gut

Question 12

Summary of a balanced diet:

Answer 12

• gives you all the essential nutrients
• six essential nutrients: carbohydrates, proteins, lipids, vitamins, minerals and water

Question 13

energy requirements in different people:

Answer 13

Dependant on activity level (e.g athletes - burning mass amounts of energy, age (teens - growth) and pregnancy (providing nutrients for another organism).

Question 14

Formula for energy found in food:

Answer 14

Temperature rise per gram (oC/g) = Temperature rise (C) / mass of the food (g)

Question 15

Flaws in the experiment (energy from food)

Answer 15

• dispersion of heat
• insulating the tube e.g with foil would minimise heat lose and retain the energy in the water

Question 16

Enzymes and digestion

Answer 16

• starch, proteins and fats are large molecules that can be broken down, they are also insoluble
• sugars, amino acids, glycerol and fatty acids are smaller molecules, they are soluble and can pass though walls of the digestive system
• the digestive system breaks down large molecules into smaller ones
• Amylase converts starch into maltose, Maltase converts maltose into glucose

e.g starch –> (amylase + enzyme) –> maltose

maltose –> (maltase + enzyme) –> glucose

• Protease convert proteins into amino acids.
• Lipases convert lipids into glycerol and fatty acids

Question 17

Summary of Bile:

Answer 17

• neutralises stomach acid and emulsifies fats
• produced in the liver, stored in the gall bladder – before released into the small intestine
• hydrochloric acid in the stomach makes the ph to acidic for enzymes in the small intestine, bile is an alkaline – it makes the conditions alkaline, enzymes in the small intestine work best in alkaline conditions
• bile emulsifies fats (breaking fats down into tiny droplets), this gives a larger surface area of fat for the enzyme lipase to work (making digestion faster)

Question 18

Summary of peristalsis

Answer 18

• muscular tissue down in the alimentary canal
• squeezing action (waves of circular muscle contractions)
  prevents the clogging of the gut

Question 19

Summary of the alimentary canal:

Answer 19

• runs through your body
• known as the gut

Mouth:

• salivary glands in the mouth produce amylase enzyme in saliva
• teeth breaks down foods

Oesophagus:

• muscular tube that connect mouth and stomach

Liver:
- bile is produced

Gall bladder:
- bile is stored

Large intestine:
- colon
- excess water is absorbed

Rectum:
- where faeces are stored (made up of indigestible foods)

Stomach:
- pummels food with muscular walls
- produces protease enzyme and pepsin
- produces hydrochloric acids to kill bacteria, give optimum ph for protease enzyme

Pancreas:
- produced protease, amylase and lipase enzymes
releases enzymes into small intestine

Small intestine:
- produced protease, amylase and lipase enzymes to complete digestion
- where nutrients are absorbed out of the alimentary canal and into the body
- first part is the duodenum, second is the ileum

Question 20

Summary of villi:

Answer 20

• helps with absorption
• small intestine is adapted for this function
• large surface area for absorption because there are millions of villi in the small intestine
• each cell in the villus has its own microvilli - little projections that increase the surface area more
• villi has a single permeable layer of surface cells and a good supply of blood to assist quick absorption